Heat exchanger



July 4, 1961 c. BAILYS HEAT EXCHANGER 2 Sheets-Sheet 1 Filed July 26,1957 C. BAILYS HEAT EXCHANGER July 4, 1961 2 Sheets-Sheet 2 Filed July26, 1957 United States Patent 2,991,047 HEAT EXCHANGER Carl Barlys,Detroit, Mich., assignor to Borg-Warner COI'POl'fitlOH, Chicago, 111., acorporation of Illinois Filed July 26, 1957, Ser. No. 674,516 2Claims.(Cl. 257-130) This invention relates to heat exchangers and, moreparticularly, to a heat exchanger of the tube sheet type fabricated froma plurality of sheets of metal selectively bonded each to the other atpredetermined zones to define intermediate unbonded zones which may becomplementally shaped, as by hydroformin-g and the like, to form spacedtubes for passage of fluid.

This invention is primarily directed to a heat exchanger of the statedtype in which a portion of the web between the tubes remains unbonded,in which a plurality of fins are formed in the web and in whichtheseveral plies forming the fins are separated to form single-thicknesspanels so that the total heat exchange surface area is substantiallyincreased.

A primary object of the invention is, therefore, to provide a heatexchanger of the stated type having all of the advantages of themultiple-sheet construction, yet exhibiting a substantial increase inheat transfer area.

Another object of the invention is to provide a heat exchanger of themultiple-sheet type having a plurality of parallel integral tubesseparated by webs having a plurality of angularly extending integralfins in heat conductive relation thereto, in which the several pliesforming the fins are separated to reduce the effective thickness of thefins and to form passages therebetween for the flow of air so thateflicient heat transfer is aiforded.

Another object of the invention is to provide a heat exchanger of thetype described, in which the fins are integral with the tubes, inintimate heat conducting relation thereto and are so formed to eflfectturbulence in the heat exchange fluid during the course of its passagetherethrough.

A further object of the invention is to provide a heat exchanger of thestated type characterized by ease of manufacture, efllciency andfacility of use, convenience in form, and improved functionalcharacteristics.

A more particular object of the invention is to provide a heat exchangerof the tube sheet type in which a plurality of sheets of similar metalare integrally bonded at preselected zones, in which tubular passagesare formed in certain of said unbonded zones for the flow of heatexchange fluid, in which the sheets in others of said unbonded zones areslit or partially severed therefrom to form strips which are bent toassume an angular relation with respect to the plane of the sheets thusforming a plurality of openings for the flow of heat exchange fluid andin which each strip is separated to form a plurality of single fins forsecondary heat exchange between the tubular passages and fluid flowingthrough the fins.

A final object of the invention is to devise a method for making a heatexchanger of the stated type in which the fin formation is effected insuch a manner that torsional stresses are substantially reduced and inwhich the formation of single-thickness fins is facilitated.

Other objects and features of the invention will be readily apparent tothose skilled in the art from the specification and appended drawingsillustrating certain preferred embodiments in which:

FIGURE 1 is a front elevational view of a heat exchanger made inaccordance with the present invention;

FIGURE 2 is an edge view showing a preform of the present heatexchanger, in an intermediate state of formation, in which parallelbonded zones of a multiple-sheet unit are illustrated;

FIGURE 3 is a view similar to FIGURE 2, but showing a heat exchangerpreform in the next subsequent stage of development in which certain ofthe unbonded zones are formed into spaced parallel tubes forpassage offluid;

FIGURE 4 is an enlarged fragmentary sectional plan view of a heatexchanger fin made in accordance with the present invention;

FIGURE 5 is a sectional plan view taken substantially on line 5-5 ofFIGURE 4; and

FIGURE 6 is an enlarged elevational sectional view taken substantiallyon line 6-6 of FIGURE 4.

Referring now to the drawings and more particularly to FIGURE 1, theheat exchanger of the present invention is in the form of a tube sheetindicated generally by reference numeral 10 and in the illustratedembodiment includes a first sheet 6 of metal, such as aluminum or thelike, and a second sheet 8 of similar metal bonded to the sheet 6 atpredetermined zones to define headers consisting of an upper manifold 12and a lower manifold 14, and a fin unit or matrix 16 interposedtherebetween and having a plurality of integrally formed parallel tubes18 connecting the manifold 12 and the manifold 14 and spaced each fromthe other by webs 19.

The tubular passages 18 of the present heat exchanger may be integrallyformed by the process of the Reynolds Metals Co. described in theFebruary 1956 issue of the magazine Modern Metals, or by similarprocesses, such as the Roll-Bond process. In the present disclosure theterm tube sheet has the same meaning as in those processes and refers toan integral combination of tubing and webs connecting the tubing, thetubing and webs being formed from a blank comprising a plurality ofsheets of metal integrally bonded at preselected zones to defineunbonded Zones therebetween.

According to the present invention certain of the unbonded zones areexpanded to form the tubular passages 18 while intervening unbondedzones, forming major portions of the webs 19 joining adjacent tubes 18,are slit along parallel lines to form contiguous strips. The strips ofeach web 19 are shaped, by bending or the like, to form a fin section 20having a plurality of multi-ply fins 22 spaced each from the other todefine openings 23 therebetween for free passage of cooling fluid, orfluid to be cooled, such as air or the like, in a directionsubstantially perpendicular to the plane of the web 19. It will be notedthat the unbonded fin matrix constitutes substantially all of theunbonded areas between the conduits to enhance heat transfer. In thepresent instance, the fins 22 are angularly disposed with respect to theplane of the web 19 and are desirably bent into the configurationillustrated by stamping or the like. The particular shape of the fins 22shown is characterized by rigidity and freedom from torsional stresses,and in accordance with the present invention, this construction isamendable to separation of the sheets 6 and 8 in the area of the fins 22so that the effective heat transfer area is substantially increased.

Referring now more particularly to FIGURES 4 and 5, each of themulti-ply fins 22 includes separate panels 24 spaced each from the otherto form therebetween passage 26 substantially equal in width to theopenings 23. Each of the fin panels 24 may be considered asingle-thickness fin and includes a pair of curved portions 28 extendingoutwardly in both directions from the plane of the web 19, and a centralportion 32 extending substantially perpendicular to the plane of the web19 and joining the portions 28. It will be noted that the several finpanels 24 diverge each from the other to form the passage 26. Theportions 32 are shown as being parallel each to the other but it will beappreciated that they may assume any relation. For instance, theportions 32 may be bowed.

In forming the heat exchanger of the present invention, the sheets 6 and8 are provided with a suitable parting compound along parallel paths.Certain of these paths are for the formation of the passages 18 whilealternate paths are for the formation of the fins 22. The sheets arethen juxtaposed and subjected to a hot rolling operation to join thesheets in the zones between the paths of parting compound. The passages18 are then hydraulically formed in the conventional manner so that theblank assumes the configuration shown in FIGURE 3. The blank is thenprovided with a plurality of spaced parallel slits between each pair oftubes 18. The strips between each pair of slits are then bent to formthe multiply fins 22. Then the fins 22 are split by means of a wedge,drift, or other suitable means to form the separate panels orsingle-thickness fins 24. It is contemplated that the panels 24 of theseveral fins 22 may be conveniently separated simultaneously.

It will be apparent from the foregoing description that when the presentdevice is used, for example, as a heat exchanger for an air conditioningsystem that fluid to be cooled or liquified may pass into the uppermanifold 12 and thence downwardly through the several tubes 18 to themanifold 14. During the course of its passage, the fluid is subject toheat exchange with air flowing through the openings between the severalmulti-ply fins 22 and through the passages 26 defined by the severalsinglethickness panels forming a part of each fin 22. It will beappreciated that the air may be at a temperature level higher or lowerthan the temperature level of the fluid. The air flows into contact withthe several tubes 18 to elfect primary heat exchange, while secondaryheat exchange is afiorded by contact of the air with the several panels24 of the fins 22. In the present construction free flow of heat betweenthe tubes 18 and the fins 22 is made possible by the fact that theportions of the intervening webs are integrally bonded, there being nosolder or brazing therebetween to hinder this flow of heat. The gradualcurvature of the distorted portions 28 assumes freedom from torsionalstress in these areas.

The heat exchanger of the present invention exhibits importantadvantages over prior constructions in that the conduction of heat fromthe walls defining the passages 18 to the fins 22 is facilitated, sinceboth sides of the fin panels 24 are exposed to the flow of air. Sincethe thickness of each section is only a fraction of the thickness of thecomposite blank, the passage of heat from the fin panels is enhanced.The present heat exchanger is a unitary structure which may beconveniently formed. According to the present method, the passages 18may be formed after the slitting step, if desired.

While I have described my invention in connection with certain specificembodiments thereof, it is to be understood that this is by way ofillustration and not by way of limitation and the scope of my inventionis defined solely by the appended claims which should be construed asbroadly as the prior art will permit.

I claim:

1. A heat exchange element comprising at least one pair of relativelyspaced conduits and a fin matrix joined to said conduits and extendingtherebetween, said fin matrix comprising two plies of heat conductivesheet material bonded together in areas at their junction with saidconduits and unbonded in the areas intermediate said conduits, all ofthe unbonded areas of said plies being provided with spaced parallel finelements partially severed therefrom and extending thereacrosssubstantially normal to said conduits and disposed in relatively spacedconfronting pairs between and at lateral angles to said conduits, saidfin elements being joined to one another and to the conduits in thebonded areas adjacent to said conduits.

2. A heat exchange element as defined in claim 1, wherein the finelements are joined to one another and to the conduits in the bondedareas adjacent to said conduits by adjacent distorted portions of thefin elements.

References Cited in the file of this patent UNITED STATES PATENTS1,823,003 Replogle Sept. 15, 1931 2,375,334 Valyi et al. May 8, 19452,582,358 Schoellerman Jan. 15, 1952 2,647,731 Ludlow Aug. 4, 19532,652,233 Przyborowski Sept. 15, 1953 2,690,002 Grenell Sept. 28, 19542,759,247 Grenell et a1. Aug. 21, 1956 2,779,086 Rieppel et a1. Jan. 29,1957

